This research program will not change from its previous objectives. We propose to determine the biologic relevance of the heterophile transplantation antigen system in human renal transplantation. We will explore the use of complement fixation, hemagglutination, immunofluorescence, migration inhibition, blastogenic transformation, and gel-diffusion as methods of detecting the appropriate antigens in the human. We then expect to determine the genetics of the system and the effect of compatibility and incompatibility upon clinical transplantation results.